Motor-reducer, in particular for mixers, stirrers and similar machines

ABSTRACT

The invention refers to a motor-reducer to be used, in particular, for mixers, stirrers and similar building machines, comprising an electric motor ( 2 ) and e reducer ( 3 ) kinematically connected via a gear train ( 4, 6, 8 ) and with a relevant output shaft ( 9 ) intended for moving a mixing tank ( 10; 110 ); the motor-reducer ( 1 ) is provided with a box-shaped shell ( 15 ) made of insulating material, open laterally, able to include the casing ( 12 ) of the electric motor ( 2 ), closable by a flange ( 19 ) made of electrically insulating material and interposed between the motor ( 2 ) and the reducer ( 3 ). (FIG.  1 ).

SPECIFICATION

[0001] The present invention refers to a motor-reducer to be used, inparticular, for mixers, stirrers and similar machines of the buildingtechnical field. Numerous attempts have been made so far to solve theproblem of the electrical insulation in building machines of the abovementioned type.

[0002] To improve the electrical insulation in motor-reducers used inbuilding machines such as mixers and stirrers, a first approach is toinsert the motor-reducer assembly within a cabin made of plasticsmaterial and containing all the above components. This solution,however, implies increased overall dimensions of the machine's parthousing the motor and reducer.

[0003] A further attempt to solve the problem of the electricalinsulation in a motor-reducer provides for separating the electric motorfrom the reducer, insulating only the motor and connecting the latter tothe reducer via drive belts made of insulating material. This solutiondoes not allow a direct connection between the motor and the reducer.

[0004] The main object of the present invention is to overcome the saiddrawbacks by constructing a motor-reducer provided with a dualinsulation for the electrical parts.

[0005] This result has been achieved, according to the invention, byproviding a motor-reducer having the characteristics indicated in theclaim 1. Further characteristics being set forth in the dependentclaims.

[0006] The advantages deriving from the present invention lieessentially in the fact that the motor-reducer provides a dualinsulation of the electrical parts; that an improved work safetyconditions are obtained; that the motor-reducer in question has anoutput shaft on which a mixing tank for mixers and stirrers can bedirectly attached; that although the invention is relatively easy tocarry out, it allows the construction of an extremely safe and resistantproduct able to maintain its characteristics unaltered over the wholeservice life of the machine.

[0007] These and other advantages and characteristics of the inventionwill be best understood by anyone skilled in the art from a reading ofthe following description in conjunction with the attached drawingsgiven as a practical exemplification of the invention, but not to beconsidered in a limitative sense, wherein:

[0008]FIG. 1 is a schematic view in longitudinal section of a possibleembodiment of a motor-reducer according to the present invention;

[0009]FIGS. 2A and 2B show, respectively, a side view and a front viewof a first possible example of application of the motor-reducer inquestion;

[0010]FIGS. 3A and 3B show, respectively, a side view and a front viewof a second possible example of application of the motor-reducer inquestion;

[0011]FIGS. 4A and 4B show, respectively, a side view and a front viewof a third possible example of application of the motor-reducer inquestion;

[0012]FIG. 5 shows a side view, with parts taken away, of a fourthpossible example of application of the motor-reducer in question;

[0013]FIG. 6 is a schematic view in longitudinal section of a furtherpossible embodiment of a motor-reducer according to the presentinvention.

[0014] The description which follows is made with reference to theschematic drawings of the attached figures wherein numeral (1)designates a motor-reducer as a whole, that is, comprising an electricmotor (2) and a reducer (3). The electric motor (2) may be of known typehaving two to four poles and, accordingly, it is not described indetail.

[0015] The output of the motor (2) exhibits the toothed end (4) of ashaft (22) on which the relevant rotor (5) is keyed. The rotor's shaft(22, 4) is in meshing engagement with the first gear of a train of gearshaving parallel axes and making part of the reducer (3). The first gear(6) is engaged, via a pinion (7) being coaxial and solid with the samegear (6), with a second gear (8) provided with the output shaft (9) ofthe reducer (3). Possibly mounted directly on the output shaft (9),which can be conical as in the example of FIG. 1, is a mixer's tank(10). The output shaft (9) may be cylindrical as well, so as to allowthe mounting thereof in a stirrer or other similar building machine.

[0016] Shown in FIGS. 2A-B, 3A-B and 4A-B are respectively, a mixer withrotary support, a drum mixer and a wheelbarrow mixer; in these figures,the building machine is designated with numeral (11), the tank with (10)and the motor-reducer with (1), while the other parts have not beennumbered because of known type. In FIG. 5, the motor-reducer (1) isassociated with the tank (110) and a stirrer (111). It will beappreciated that further application examples are possible, as thoseskilled in the art can easily understand.

[0017] According to the invention, the body of the electric motor (2)that is, the casing (12) holding the rotor (5), stator (13) and relevantwindings, and the electric system's section (14), are housed within acoating shell (15) of insulating material.

[0018] The shell (15) comprises a main body having a substantiallycylindrical shape, open in correspondence of a base, and an auxiliarybody (16), located on top in the example of FIG. 1, able to enclose thegroup (14) of the electrical system's components (not shown) which areoutside the motor (2).

[0019] The said electrical system (14) can be constructed and mountedseparately from the shell (15), and still leaving unaltered theoperational capacity of the second electrical protection of theassembly. This solution being not illustrated for the sake ofsimplicity.

[0020] The shell (15) is provided with aeration apertures (18) incorrespondence of the region of fan (17) of the electric motor (2) (leftside in FIG. 1).

[0021] On the opposite side, the shell (15) is closed by a flange (19)which is made of electrically insulating material and interposed betweenthe right-side part of casing (12) and the reducer (3). In particular,the flange (19) is fastened by screw means (20) to the casing (12), andthe connection portion (21) of reducer (3) is fastened on the flange(19); the screws (20) are isolated from the casing (12). To ensure theinsulation degree around the rotor's shaft, in correspondence of theportion of shaft (22) on which the rotor (5) is fixed, there is provideda bush (23) in insulating material which, therefore, results interposedbetween the shaft (22) and rotor (5).

[0022] In this way, it is possible to fulfill the requirement of dualelectrical insulation required for mixers, stirrers and similar buildingmachines.

[0023] In the illustrated example of FIG. 6, the insulating bush (23)extends almost over the whole length of the shaft (22) of rotor (5).

[0024] Moreover, in place of screws (20) which, in the example of FIG.1, fix the casing (12) to the portion (21) of reducer (3), provision ismade for two sets of screws designated, respectively, with (120) and(121). The screws (120) and (121) may be disposed along respectiveconcentric circumferences; in FIG. 6, the representation in longitudinalsection allows only one of screws (120) and one of screws (121) to beseen. The screws (120) connect the motor's casing (12) to the flange(19). The screws (121) connect the flange (19) to the reducer (3), incorrespondence of said connection portion (21). Practically, in thisembodiment, the insulation of the rotor is developed over an extensiongreater than in the example of FIG. 1 and, besides, the connectionbetween the motor and reducer is made by connecting the flange to thetwo elements independently, that is, by means of the two separate setsof screws (120) and (121).

1. Motor-reducer to be used, in particular, for mixers, stirrers andsimilar building machines, comprising an electric motor (2) and ereducer (3) kinematically connected via a gear train (4, 6, 8) and witha relevant output shaft (9) intended for moving a mixing tank (10; 110);motor-reducer (1) characterized in that it is provided with a box shapedshell (15) made of insulating material, open laterally, able to includethe casing (12) of the electric motor (2), closable by a flange (19)made of electrically insulating material and interposed between themotor (2) and the reducer (3).
 2. Motor-reducer according to claim 1,wherein said electric motor (2) has a shaft (22) coaxial and solid tothe relevant rotor (5) of the electric motor (2), characterized in thatsaid motor (2) is provided with a bush made of insulating material (23)fitted on said shaft (22) and interposed between the rotor (5) and thesame shaft (22).
 3. Motor-reducer according to claim 2, characterized inthat said bush (23) extends almost over the whole length of the shaft(22) of rotor (5).
 4. Motor-reducer according to claim 1, characterizedin that said flange (19) is connected to the motor's casing (12) by afirst set of screw (120) and to a connection (21) portion of the reducer(3) by a second set of screw (121).
 5. Motor-reducer according to claim1, characterized in that the said shell (15) is joined or is associablewith a box-shaped body (16) made of insulating material and able toenclose the group (14) of components of the electrical system which areoutside the motor (2).
 6. Motor-reducer according to one of thepreceding claims, characterized in that the said output shaft (9) isdirectly connected with the tank (10; 110) of the building machine (11;111).